Circuit-controlling apparatus



Dec. 11, 1945. K. A. OPLINGER CIRCUIT-CONTROLLING APPARATUS Filed Jan. 26, 1943 INVENTOR H Op/fnger.

[nju/af/an e w e 3 WW 2 a a a 460%, 7 7 w e e 5 2 W a L. W rna a F 5 rm ma 5 Z Patented Dec. 11, 1945 CIRCUIT-CONTROLLING APPARATUS Kirk A. Oplinger, Verona, Pa., assignor'to -West- -inghouse Electric Corporation, East: Pittsburgh,

Pa.,.'a corporation of Pennsylvania Application January 26, 1943, Serial No. 473582 6 Claims.

This invention relates to electrical apparatus and, in particular, to circuit controlling apparatus.

This application is a continuation-in-part of my copendin-g. application, Serial No. 416,171, filed October 23, 1941.

In electrical systems, switches and electromagnetic operating devices therefor have been utilized for controlling and establishing given circuits. The electromagnetic devices usually consist-of a core member, a Winding disposed to .be energized magnetically associated therewith, and an. armature disposed for movement for actuating the switch to eflect a switching operation when the winding is energized.

Where weight is a consideration in the type of circuit-controlling device utilized, an electromagnetic apparatus of the type having a. variable magnetic gap between the armature and the core memberis employed as the actuating mechanism in contrast-with the type of electromagnetic apparatushaving ,an overlapping gap. The variable magnetic-type of .electromagnet is .usuallysmaller and less complicated-than .the overlapping gap type of electromagnetic devices.

Wherexhe variable gap type of electromagnetic devicescareaemployedwith a plurality of switches .for efiectingmmgressivesswitching operations, it -isr.fonnd ithat :the opposing forces of the switches .andthe nperating .device :are unbalanced during operation, sand that stability of operation is .not obtained. iEurt'her, :the electromagnetic device willnntchave thexvoltage sensitivity over its Working mange required ifor sensitive operations such .as in voltage regulators foraircraft applications.

:objectof :this invention .is .to provid in a circuit-controlling apparatus having a plurality .of;spring biased progressively .operated switches :forcompensatingforrthe change in forces of the spring-.biasedswitches as the switching operations are effected to give :a substantially uniform stazbilityolf operation of the .switches.

A more specific object of this invention is to ,providexin an electromagnetic device disposed for actuating 'a plurality of spring biased progres- .-sivelygoperated switches for compensating for the change .in balance of the forces of the electromagnetic device and the switchesresulting from .theoperation-of the switches.

Other objects of this invention will become apparent from the following description when taken .in conjunction with the accompanying drawin .in which:

Figure 1.is.a view in-elevation of the circuit- .controlling apparatus .of this invention;

Fig, 2 is a view of a part of the electromagnetic device of .1 taken along the .line LII-5H thereof;

Fig. 3 is a plan view,greatly enlarged,-of another part of the electromagnetic device. ofjFig. '1 taken along theline III-III thereof; and

Fig. 4 is a graph,-the curves of .whichrepresent the opposing forces which are balanced in .the circuit-controlling apparatus of this invention.

Referring to Fig. 1,..this invention .is .illustrated as appliedtoa circuit-controlling device H1 comprising the switchingapparatus. I 2 and an electromagnetic device Iddisposedto controlthe operation of'the switching apparatus 12.

Th switching apparatus l2 illustrated .comprises a plurality of elongated:self-biasedspring leaf, members 16 having-one of theirendsinsulated from each other by meansroflayers llof suitable insulating material, such .as fishpaper, and fixedly supported with respect toeachother in an insulating clampingmemberlil, the .details of which are notshown. The otherends of the spring leaf members I6 are free to move away from an adjustable stop 20, the stop being provided with a beveled or sloped ..suriace,22 for receiving and spacing the ends of the biased members IzB for limiting their movement in the self-biasing direction.

Each of the sprin leaf members l6 is-of-good conducting material, such as beryllium copper alloy, and carries a contact button 24 near its free end. The contact .buttons 24 .are so positioned that as thespring leaf members .16 .are actuated :away from thesloped surface 22=0f the stop 20, the contact buttons are progressively actuated into-engagement. In practice, themrojecting ends of thefixed spring leaf'members -l;6 are connected to'different sections of aresistor (not shown) by suitable .conductors, .so that *as the spring members 46 areeactuatedtothecircuit closingposition, the sections :of .the resistor-are progressively shunted by the .progressively closed contact buttons 24 carried by the spring leaf member 16.

For amore'complete descriptionrof th details and construction of the switching apparatus l2, reference may be had to Patent No. 2,246,301 which issued June 17, 1941, to .C. R. Hanna et a1. and which is assigned to the assignee of this invention.

The electromagnetic device II may'be of .any form, and as illustrated comprises a coremember 26 having an energizing winding 228 mounted thereon, the winding bein disposed to Joe "energized in a predetermined manner from a suitable source of power (not shown).

ber 31, and is disposed to be pivotally secured to the depending legs 34 of the bracket 36 by means of the spring pivot member 46. The positioning of the armature member 36 and the function of the button 38 in the structure of this invention will be explained more fully hereinafter. As more clearly illustrated in Fig. 2, the spring pivot member is of substantially U-shape, the base of the pivot member 46 being secured to the armature member 36, as by means of the rivets or screws 42, or where desired, as by means of copper'brazing. The legs of the spring pivot member 40 are spaced in the same manner as the divided legs 34.0fthe bracket 36, and aresecured to the legs 34 by means of the screws 44.

I Referring again to Fig. 1, the member 46 of the armature member36 constitutes a driving member disposed to actuate the spring leaf members IE to effect progressive switching operations as the armature member 36 is moved. The tip 48 of i the driving member 46 is of insulating material for insulating the armature member 36 from the conducting spring leaf members l6.

In order to balance the magnetic pull on the armature member 36 when the winding 26 is energized, a coil spring member 56 is'provided. One end of the coil spring'56 is secured to the lower end of the armature member 36, as illustrated in Fig. 2, the endof the spring 56 being hooked through suitable openings 52 in the armature 36. The other end of the spring is secured to an adjustable screw 54 which is carried on one end of the bracket 56, the other end of the bracket 56 being secured to the bracket member 36 in any suitable manner. By adjusting the position of the screw 54, the tension of the coil spring 56 may be so adjusted that the force of the spring will balance the magnetic pull of the electroma netic device [4 throughout the operating range of the armature 36.

As the spring leaf members l6 are progressively actuated to their circuit closing position, the stiff ness of the spring leaf members l6 increases, depending upon the number of spring leaf members l6 that form the switching assembly. This stiffness or resistance of the spring leaf members l6 to the actuating force for effecting a circuit closing operation is a variable, varying over the operating range of the armature member 36. In order to offset the variable stiffness factor of the spring leaf assembly, a magnetic trimmer 58 is provided for cooperating with the electromagnetic device I4 for compensating for the change in ba1- ance of the forces of the circuit-controlling apparatus due to the change in the stiffness factor of the switching members as switching operations are effected.

As more clearly shown in Fig. 3, the magnetic trimmer 58 comprises a substantially U-shaped member 60 of magnetizable material having one of its legs 62 secured to the core member 26 of the electromagnetic device l4 as by means of a close press fit. The other leg 64 of the U-shaped member '60 terminates opposite the core member 26 on the opposite side of the armature 36. Thus, as

to the screw '66. The size of the screw 66 and the v air gap between the screw and the armature member determines the magnetic pull applied to the armature member by the magnetic trimmer in opposition to' the main magnetic .pull of the electromagnetic device. In this embodiment, the screw 66 has a small surface area as compared to the surface area of the main core member 26 and the gap betweenthe screw 66 and the armature member 36 is maintained relatively small as compared With the gap between the armature member 36 and the main core member 26. W

As illustrated in Fi 1, and moreclearlyshown in Fig. 3, the contact button 38 carried by the armature member 36 is of a size sufficient to insure that the armature member 36 is maintained.

in a position where the air gap betweenthe adjusting screw 66 and the armature member 36 is smaller than the air gap between the armature member 36 and the main core member 26 when the button 38 is seated against the core member and for all operative'movement of the armature member 36 over the working range of from open to closed positions of the leaf spring members l6. By positioning the armature member in this manner, a small air gapbetween the armature member 36 and the adjusting screw 66 provides for applying a magnetic force to the armature member 36 which increases in a non-linear rela tion as the armature member approaches the screw'66, such increasing :force being substantially equal but opposite to the bias 0r stiffness of the leaf springs I6 as they are actuated to acircuit closing position.

The operation of the cir'cuit-controllingapparatus of this invention can be best explained by reference to the curves of Fig. 4. In this graph, the horizontal line 12' represents the ar- 'mature travel from a position where the contacts are closed to the position where the contacts are open, as represented by the vertical lines and 76, respectively. Forgetting for the moment the presence of the magnetic trimmer 58, the magnetic pull of the electromagnetic device. [4 on the armature member 36 as the armature travels from the circuit closed position to the circuit open position is represented by the curve 18. In the graph, this curve 18 is represented as a negative force "as opposed to the forces which will be illustrated above the horizontal line 12.

Opposing the magnetic pull 18 is the force of the spring pivot 40 and the force ofv the adjustable spring 56, as represented by the curve 60.

As is evident, these opposin forces represented by the curves l8 and substantially balance each other throughtout the operating range or path of movement of the armature 36. The

assasoo 3 movement of the armature member 36 through the :total air gap between the screw 66 :and :the

core member 26 if such movement were per- :mitted. :Howeven'the button 36 limits the movespring member '50. stiffness factor of the spring leaf members 126 -is represented in the craph by the curve 62,:and as illustrated opposes the forces represen'tedby the 'curve 86. Thus, in

effect, the forces of the pivot member 40 and the adjustable spring member 60 are opposed throughout the operating range of the armature 36 from the circuit closed position to the circuit opening position by the sum of the forces representedlby the curves 1-8 and 82. The non-linear former the leaf spring 16 as represented by the curve 62 is, however, a small portion of the total force opposing the force of the pivot and main spring represented by the curve 80. 'In practice, it is impossible -to so adjust the tension of the spring 56 to balance these opposing forces even though the force :of the leaf springs I6 is small to givea substantial linear stability or relation between the voltage and deflection of the armature member 36 over the entire range of travel of the armature.

- By adding the magnetic trimmer 66, which constitutes arr-extension of the core member 26, it is found that the magnetic pull of the leg 64 of the U-shapedmember Gil-and the'magnetizable screw 66 carried thereby on the armature member'86 is a variable, depending upon the position A of the armature with respect to the screw member '66 and the size of the screw, the magnetic pull of the trimmer increasing as the armature 36 approaches the screw member 66 and as the magnetic pull of the core member '26 on the armature 36 decreases. The magnetic 'pull of "the trimmer through the screw 66 on the armature member 3'6 in opposition to 'the'main force represents a small percentage of the main force applied to the armature member by the main core member 26. The magnetic pull of the trimmer on the armature member 36 may be varied by 'adjusting the position of the screw member 66 to vary the size of the air gap between the screw 66 and the armature 36.

As described hereinbefore the leaf springs l6 have a non-linear stiffness factor or force as rep resented by the curve 62 of Fig. 4. The travel of the armature member 36 is limited to that small amount required for actuating the leaf sprin [6 from open to "closed positions, and it is necessary, therefore, to provide a positive force for only that travel which'will be in opposition to the non-linear force of the leaf springs 16. This is accomplished by the use of the trirnmer described hereinbefore, the screw 66 and a small .air .gap provided thereby giving a small non-linear force which is in opposition to the stiffness factor of the leaf springs l6.

Thus, by suitably adjusting the screw member 66, a magnetic pull curve 84, as represented in Fig. 4, may be obtained which is in opposition to but which will substantially match the nonlinear curve 82 representing the stiffness factor of the progressively operated switching members Hi. The. magnetic trimmerthuscompensates for any change in the balance between :the pulls exented on .the armature resulting from a progressive :operation of the .spring biased switch .membars 16, and results in :the obtaining .of 'astable operating curve, as represented by .66, which is substantially linear vwithrespect to themovement of the armature throughoutithe operating range of thearmature.

The net force represented 'by curve 86 is atways "in one direction to tend to effect an operration of the leaf springs 16 toward an open position "in opposition to the force of -the pivot and'main spring which tend to operate :the leaf spring 46 'to a circuit closing position. In :other words, by positioning -the armature member 36,; as described -hereinbefore, so that the gap between the screw 66 and the armature member 86 is smaller than the gap between the armature member 36 and the core member 26, that is, with the armature member-36 maintained to-one side of the center line of the air gap between the screw 66 and the core member '26, the trimmer applies a definit positive force in one direction to the armature member 36 at all times while the energizing winding '26 is energized. This positioning of the armature member 36 in the gap insures a gradual movement of the armature member 36 to actuate the leaf spring members I6 in response to a slight decrease in the energiza'tion of the=energizing winding '26.

Through the use of the magnetic trimmer, it is possible to operate a larger number of the progressively operated spring biased switching members 16, as the magnetic pull of the trimmer can be matched against the stiffness factor of the biased switching members regardless of the number of switching members employed. Further, since all the forcesof the circuit-controlling apparatus are in substantial balance regardless of the number of switching operations effected, an increased voltage sensitivity response of the circuit-controlling apparatus is obtained, it "being found that substantially the same voltage change is required'for each switching operation throughout the progressive operation of the switching members. Further, where, in service, it is found necessary to 'makechanges in the switching members, the-circuit-controlling apparatusof this invention can be readily adjusted by adjusting the position of the screw 66 with respect to the armature member to give a substantially perfectly balanced circuit-controlling apparatus.

Although this invention has been described with reference to a particular embodiment thereof, it is, of course, not to be limited thereto except insofar as is necessitated by the scope of the appended'claims.

I claim as'my invention:

1. In a circuit-controlling apparatus, in combination, .a plurality of spring biased switches, a spring biased armature member for actuating progressively the spring biased switches to closed positions, electromagnetic means comprising a core member and a winding thereon disposed to be energized to exert a magnetic pull on the armature member to actuate it to progressively release the spring biased switches, means comprising an extension of the core member of the electromagnetic means disposed to exert a magnetic pull on the armature member in opposition to an inversely varying with the magnetic pull of the core of the electromagnetic means, the extension and core member being disposed on opposite sides of the armature member to procompensating for the change in-balance'between the forcesof the biased switches, armature biasing spring and the magnetic pull of the electromagnetic means exerted on the armature member resulting from the progressive release of the spring biased switches 2. In a circuit-controlling apparatus, in combination, a plurality of spring biased switches, a springbiased armature member for actuating progressively thespringbiased switches to closed positions, electromagnetic means comprising a core member and a winding thereon disposed to be energized to exert a magnetic pull on the armature member to actuate it to progressively release the spring biased switches, means comprising a substantially -U-shaped member of magnetizable material having one of its legs disposed on one sideof the armature member secured to the core member and the other leg terminating opposite the cor member on the opposite side of the armature member, means disposed to limit jthe movement of the armature memberraway from saidother leg towards the core member and. saidone leg when the electromagnetic means is energized, said other leg of the U-shapedmember exerting a magnetic pull on. the armature member in opposition to the magnetic pull of the core and said oneleg, said limiting means cooperating with said other leg to provide an air gap between said other leg and the armature member that is smaller at all times than the air gap between the core member and the armature member to insure the exertion of a continuous non-linear magnetic pull by said other leg in one direction on the armature memher when the electromagnetic means is energized, the non-linear magnetic pull of the extension compensating for the chang in'balance between the forces of the biased switches, armature biasing spring and the magnetic pull of the electromagnetic means'exerted on the armature member resulting from the progressive release of the spring biased switches.

3. In a circuit-controlling apparatus, in combination, a plurality of spring biased switches, a spring biased armature member for actuating progressively the spring biased switches to closed positions, electromagnetic means comprising a core member and a winding thereon disposed to be energized to exert a magnetic pull on the arma ture member to actuate it to progressively release the spring biased switches, means comprising an extension of the core member of the electromagnetic means disposed to exert a ma netic pull on the armature member in opposition to an inversely varying with the magnetic pull of the core of the electromagnetic means, the extension and core member being disposed on opposite sides of the armature member to provide a predetermined gap therebetween, means disposed to limit the movement of the armature member towards the core member when the electension in one-direction on the armaturemember when the electromagneticmeans is energized, the non-linear magnetic pull of the extension compensating for thechange in balance between the forces of the biased-switches, armature biasing spring andthe-magnetic pull of the electromagneticrmeans exerted on the, armature member resulting from th progressive release of the spring biased switches, and means for manually adjusting the, extension to adjust the gap and efiect an adjustment in the magnetic pull of the extension on the armature member.

4. In a circuit-controlling apparatus, in combination, a plurality ofspring biased switches, a spring biased armature member for actuating progressively the spring biased switches to closed positions, electromagnetic means comprising a core member and a winding thereon disposed to be energized to exert a magnetic pull-on the armature member to ,actuate it to progressively release the spring biased switches, means comprising a substantially U -shaped member of magnetizable material having one of its legs disposed on'one side of the armature member-securedto the core member and the other leg terminating opposite the core member on the oppositeside of the armature member, means disposed to limit the movement of the armature member away from saidbther leg towards the core member and said one leg when the electromagnetic means is energized, said other leg of the U-shaped 'member exerting a magnetic pull on the armature member in opposition to the magnetic pull of the core and said one leg, said limiting means 7 cooperating with said other leg to provide an air gap between said other leg and the armature member that is smaller atall times than the air gap between'the core member and the armature member to insure the exertion of a continuous non-linear magnetic pull by said other leg in one direction on the armature member when the electromagnetic means is energized, the nonlinear magnetic pull of the extension compensating, for the change in balanc betweenthe forces of the biased switches, armature biasing spring and the magnetic pull of the electromagnetic means exerted on the armature member resulting from the progressive release of the spring biased I switches, and means carried by said other leg for manually adjusting the magnetic pull by said other leg on the armature member.

' 5. In a circuit-controlling apparatus, in combinatioma plurality of spring biased, switches, a spring biased armature member for actuating progressively the s'pring'biased switchesto closed on the opposite side of the armature member,-

means carried by the armature member disposed to limit the movement thereof away from said other leg toward the core member and said one leg when the electromagnetic means is energized, said limiting means cooperating with said other leg to provide an air gap between said other leg and the armature member that is smaller at all times than the air gap between the core member and the armature member to insure the exertion of a continuous non-linear magnetic pull by said other leg in one direction on the armature member when the electromagnetic means is energized, the non-linear magnetic pull of said other leg being substantially equal but opposite in force to the non-linear force exerted by the spring biased switches.

6. In a circuit-controlling apparatus, in combination, a plurality of spring biased switches, a spring biased armature member for actuating progressively the spring biased switches to closed positions, the spring biased switches exerting a non-linear force in opposition to the armature member as they are moved to closed positions, electromagnetic means comprising a core member and a winding thereon disposed to exert a magnetic pull on the armature member to, actuate it to progressively release the spring biased switches, means comprising a substantially U- shaped member of magnetizable material having one of its legs disposed on one side of the armature member secured to the core member and the other leg terminating opposite the core member on the opposite side of the armature member, means carried by the armature member disposed to limit the movement thereof away from said other leg toward the core member and said one leg when the electromagnetic means is energized, said limiting means cooperating with said other leg to provide an air gap between said other leg and the armature member that is smaller at all times than the air gap between the core member and the armature member to insure the exertion of a continuous non-linear magnetic pull by said other leg in one direction on the armature member when the electromagnetic means is energized, the non-linear magnetic pull of said other leg being substantially equal but opposite in force to the non-linear force exerted by the spring biased switches, and means carried by said other leg for manually adjusting the magnetic pull thereof to insure maintaining the force of the magnetic pull equal but opposite to thenon-linear force of the spring biased switches as they are actuated from closed to released positions.

KIRK A. OPLINGER. 

